Electric furnace smelting process based on burden structure optimization

Abstract

The application discloses an electric furnace smelting process based on charge structure optimization. A main metal material used in the electric furnace smelting process comprises the following components in percentage by mass: molten iron 25-45%; light and thin plate scrap steel 24-42%; high-purity slag iron 6-18%; scrap steel crushing material 6-12%; medium scrap steel 5-12%; heavy scrap steel 0-9%; and auxiliary materials used in the electric furnace smelting process comprise the following components: lime 20-35 kg / t of molten iron; dolomite 10-15 kg / t of molten iron; and pre-melted slag 3-5 kg / t of molten iron. The electric furnace smelting process based on charge structure optimization fully considers the influence of metal raw material structure on a smelting period, power consumption and iron resource recovery rate, finally realizes the maximization of electric furnace smelting process benefits, and plays a comprehensive role of shortening the smelting period, reducing the power consumption and improving the iron resource recovery rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steelmaking, and particularly relates to an electric furnace smelting process based on furnace charge structure optimization. BACKGROUND

[0002] Electric furnace steelmaking technology belongs to low-carbon steelmaking technology. With the increasing requirements of "carbon peak and carbon neutralization", the electric furnace steelmaking technology with low-carbon steelmaking properties urgently needs to solve a series of problems such as long smelting cycle and high power consumption, so as to adapt to the production rhythm of efficient continuous casting and reduce production cost, and ensure the market competitiveness of the economic efficiency of electric furnace steelmaking. Since the smelting cycle, power consumption and iron resource recovery rate are the three core indicators most concerned by electric furnace smelting, in addition to focusing on the electric furnace smelting cycle and power consumption, the iron resource recovery rate of scrap steel raw materials also needs to be focused on in the actual smelting process. For the actual electric furnace, under the condition of determined transformer capacity, power supply curve optimization, oxygen supply system optimization and furnace charge structure optimization are the key measures to reduce power consumption, smelting cycle and improve iron resource recovery rate. The present application focuses on the optimization of electric furnace charge structure.

[0003] There are also technologies related to the optimization of electric furnace charge structure in the prior art. For example, application No. CN200910018449.X provides a high-efficiency and low-cost electric furnace charge process, in which the main charge is molten iron accounting for 30-60% of the metal addition amount, high-quality scrap steel accounting for 5-10% of the metal addition amount, and cheap scrap steel accounting for 30-35% of the metal addition amount. However, this technology only considers the cost of scrap steel itself and does not consider the comprehensive influence of the furnace charge structure on power consumption, smelting cycle and iron resource recovery rate. Application No. CN201510079803.5 provides an electric furnace smelting optimization batching calculation method, which includes establishing raw material consumption constraint equation, product target component constraint equation, product target total weight constraint equation and optimization batching target function, and constructing a linear programming mathematical model on this basis to obtain a set of pre-batching schemes. However, this technology focuses on the control of electric furnace smelting components and the recovery of valuable residual elements, and does not consider the comprehensive influence of the furnace charge on power consumption, smelting cycle and iron resource recovery rate. Other technologies in the prior art mainly consider ensuring smooth production and using low-cost raw materials in the actual production of furnace charge structure optimization scheme, and do not comprehensively consider the comprehensive influence of the furnace charge structure on power consumption, smelting cycle and iron resource recovery rate.

[0004] In view of the above situation, it is urgent to develop an electric furnace charge structure optimization process that can comprehensively consider the influence of metal raw material structure on smelting cycle, power consumption and iron resource recovery rate, so as to maximize the benefit in the electric furnace smelting process. SUMMARY

[0005] In view of the above defects in the prior art, the purpose of the present application is to provide an electric furnace smelting process based on charge structure optimization, which fully considers the influence of metal raw material structure on the smelting cycle, power consumption and iron resource recovery rate, and finally realizes the maximization of electric furnace smelting process benefit, and plays a comprehensive role in shortening the smelting cycle, reducing the power consumption and improving the iron resource recovery rate.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The present application provides an electric furnace smelting process based on charge structure optimization, the metal main material used in the electric furnace smelting process includes the following components calculated by mass percentage: molten iron: 25-45%; light and thin plate type scrap steel: 24%-42%; high-purity slag iron: 6-18%; scrap steel crushed material: 6-12%; medium-sized scrap steel: 5-12%; heavy scrap steel: 0-9%;

[0008] The auxiliary material used in the electric furnace smelting process includes the following components: lime 20-35 kg / t of molten steel; dolomite 10-15 kg / t of molten steel; pre-melted slag: 3-5 kg / t of molten steel.

[0009] Preferably, the following steps are included:

[0010] S1, the first batch of slag is added to the electric furnace, and then the light and thin plate type scrap steel, high-purity slag iron, scrap steel crushed material, medium-sized scrap steel and heavy scrap steel in the metal main material are added to the electric furnace, and then the molten iron is added;

[0011] S2, the electric furnace is powered on and oxygen blowing smelting is carried out, after 8-15 min of power-on, the second batch of slag is added for continuous smelting, after the dephosphorization slag is discharged, the third batch of slag is added for continuous smelting, and after the carbon content and temperature of the molten steel reach the tapping requirements, the molten steel is tapped;

[0012] Among them, the auxiliary material is added into the electric furnace in three batches, and the auxiliary material includes the first batch of slag, the second batch of slag and the third batch of slag.

[0013] Preferably, in the step S1, the metal main material is added in the following way:

[0014] The electric furnace with non-continuous scrap steel adding is used, the furnace cover is opened at the beginning of electric furnace smelting, the light and thin plate type scrap steel, high-purity slag iron, scrap steel crushed material, medium-sized scrap steel and heavy scrap steel are added through the basket, then the molten iron is added, and then the furnace cover is covered for smelting; or

[0015] The electric furnace with non-continuous scrap steel adding and furnace wall opening is used, the furnace cover is opened at the beginning of electric furnace smelting, the light and thin plate type scrap steel, high-purity slag iron, scrap steel crushed material, medium-sized scrap steel and heavy scrap steel are added through the basket, the furnace cover is covered to start smelting, and the molten iron is added from the iron adding slot of the furnace wall after power-on.

[0016] Preferably, the first batch of slag material comprises lime, dolomite and pre-melted slag; the amount of lime in the first batch of slag material is 1 / 3-1 / 2 of the total amount of lime added in the auxiliary material, the amount of dolomite in the first batch of slag material is 1 / 3-1 / 2 of the total amount of dolomite added in the auxiliary material, and the amount of pre-melted slag is the total amount of pre-melted slag in the auxiliary material;

[0017] The second batch of slag material comprises lime and dolomite; the amount of lime in the second batch of slag material is 1 / 4-1 / 2 of the total amount of lime added in the auxiliary material, and the amount of dolomite in the second batch of slag material is 1 / 4-1 / 2 of the total amount of dolomite added in the auxiliary material;

[0018] The third batch of slag material is the remaining auxiliary material after the first batch of slag material and the second batch of slag material are added to the auxiliary material.

[0019] Preferably, the third batch of slag material comprises lime and dolomite, the amount of lime in the second batch of slag material is 1 / 8-1 / 4 of the total amount of lime added in the auxiliary material, and the amount of dolomite in the third batch of slag material is 1 / 8-1 / 4 of the total amount of dolomite added in the auxiliary material.

[0020] Preferably, in the metal main material, the high-purity slag iron is a block-shaped raw material obtained by processing a mixture of iron slag produced by blast furnace iron smelting; the content of iron in the high-purity slag iron is >65wt%, and the content of P2O5 is <0.5wt%.

[0021] Preferably, in the auxiliary material, the pre-melted slag comprises the following components in terms of mass percentage: CaO: 30-50%, Al2O3: 40-50%, MgO: 4-8%, and SiO2: 3-10%.

[0022] Preferably, the capacity of the electric furnace is 100-200t.

[0023] The electric furnace smelting process based on the optimization of the furnace charge structure provided by the present application has the following beneficial effects:

[0024] 1. The electric furnace smelting process based on the optimization of the furnace charge structure fully considers the influence of the metal raw material structure on the smelting period, power consumption and iron resource recovery rate, and ultimately realizes the maximization of the electric furnace smelting process, which plays a comprehensive role in shortening the smelting period, reducing power consumption and improving the iron resource recovery rate;

[0025] 2. The electric furnace smelting process based on the optimization of the furnace charge structure selects high-purity slag iron as the raw material in the metal raw material structure, which can turn waste into treasure, not only solving the problem of difficult disposal of waste materials, but also recycling iron resources;

[0026] 3. The electric furnace smelting process based on burden structure optimization of the present application, auxiliary materials in the burden structure are used to accelerate the melting of lime and dolomite in the early stage of electric furnace smelting, and a specific burden structure is used to ensure slag protection of the furnace lining, complete dephosphorization task and reduce power consumption;

[0027] 4. The electric furnace smelting process based on burden structure optimization of the present application, compared with the conventional raw material structure mainly using heavy scrap steel as the main raw material, the power consumption can be reduced by more than 10 KWh / t, the smelting cycle can be shortened by 2-5 min, the metal yield is basically maintained or even improved, and the raw material cost is also reduced. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solutions of the present application, the technical solutions of the present application will be further described below in combination with examples.

[0029] The electric furnace smelting process based on burden structure optimization provided by the present application is analyzed by establishing a mathematical model to obtain the influence of metal raw material structure on smelting cycle, power consumption and iron resource yield, and the burden structure is optimized to achieve the best economic benefit, so as to maximize the electric furnace smelting process and shorten the smelting cycle, reduce the power consumption and improve the comprehensive effect of the iron resource yield.

[0030] The electric furnace smelting process based on burden structure optimization of the present application uses metal main materials in the electric furnace smelting process, which include the following components calculated by mass percentage: molten iron 25-45%; light and thin plate scrap steel 24%-42%; high-purity slag iron 6-18%; scrap steel crushed material 6-12%; medium scrap steel 5-12%; heavy scrap steel 0-9%; wherein in the specific examples, the high-purity slag iron is a block-shaped raw material after treatment of a mixture of iron slag produced by blast furnace ironmaking, the content of elemental iron is 20-60wt%, the content of iron oxide is 20-60wt%, the content of iron element is required to be >65wt%, and other components are CaO, MgO, SiO2, P2O5, Al2O3 and other blast furnace slag residues, and the content of P2O5 is required to be <0.5wt%. The scrap steel crushed material is a social scrap steel crushed material, which is a raw material after crushing of the social scrap steel collected, and the bulk density of the crushed scrap steel can be improved.

[0031] The auxiliary materials used in the electric furnace smelting process include the following components: lime 20-35kg / t of molten steel; dolomite 10-15kg / t of molten steel; pre-melted slag 3-5kg / t of molten steel; in specific examples, the pre-melted slag includes the following components calculated by mass percentage: CaO 30-50%, Al2O3 40-50%, MgO 4-8%, SiO2 3-10%.

[0032] The principle of the structural components of the metal main material in the present application is as follows:

[0033] Hot metal: mainly considering the hot metal more convenient to accelerate the formation of liquid pool in the electric furnace, while the hot metal itself carrying carbon can quickly match the carbon to the pool to avoid the pool over-oxidation caused by oxygen blowing. Matching carbon is a necessary operation in the process of electric furnace smelting. If hot metal is not used to match carbon, pig iron or direct reduced iron is also needed to match carbon. Therefore, using hot metal to match carbon is still the best choice at present because hot metal has higher physical heat. The proportion of hot metal in the metal main material structure is selected as 25% to 45%. Mainly considering that if the proportion of hot metal is less than 25%, the matching carbon effect is not good, and the power consumption is also increased, which affects the smelting period. If the proportion of hot metal is higher than 45%, the decarburization time is too long, which affects the smelting period. Therefore, considering the power consumption and smelting period comprehensively, the proportion of hot metal is controlled to be 25% to 45%. Light and thin plate scrap: mainly considering that light and thin plate scrap has good protective arc function, and light and thin material is easier to melt in the molten steel. However, the bulk density of light and thin material is low, so the proportion of light and thin plate scrap should not be too high, otherwise the material basket and the electric furnace pool cannot guarantee one-time charging. Therefore, the final proportion of light and thin plate scrap is selected as 24% to 42%. High-purity slag iron: mainly considering that slag iron is a waste of ironmaking process, which is extremely beneficial to reduce the cost of electric furnace, and can greatly increase the recovery of metal iron in waste material. If the addition amount is less than 6%, the cost reduction effect is not good. If the addition amount is greater than 18%, the furnace condition is affected, thereby affecting the smelting period. Scrap broken material: the characteristic of scrap broken material is that it melts quickly in the molten steel, and the market price is relatively cheap. However, the scrap broken material does not have the ability of arc burying. Considering comprehensively, the addition amount is selected as 6% to 12%. Medium-sized scrap: mainly considering that medium-sized scrap has high bulk density and high molten steel yield. However, it is difficult to melt quickly, and the market price is high. Finally, the appropriate addition amount is selected as 5% to 12% to meet the total weight of scrap in the material basket, the space requirement of the material basket and the smelting space requirement of the electric furnace. Heavy scrap: heavy scrap has the characteristics of high molten steel yield. However, in the actual smelting process, too much addition of heavy scrap will lead to high power consumption, long smelting period and serious over-oxidation of molten steel pool. Finally, a little bit of heavy scrap is selected, but the addition amount needs to be controlled within 9%.

[0034] The above metal main material is considered as a whole. In the present application, a model is used to analyze a large amount of data in the production site, and the above furnace charge structure optimization scheme is obtained. The scheme can well meet the requirements of low power consumption, low smelting period and high molten steel yield. According to the market prices of various raw materials, it is calculated that such raw material structure can meet the best economic benefits of electric furnace smelting. Compared with the conventional raw material structure taking heavy scrap as the main raw material, the power consumption can be reduced by more than 10 KWh / t, the smelting period can be shortened by 2 to 5 minutes, the metal yield is basically maintained or even improved, and the raw material cost is also reduced.

[0035] The high-purity slag iron needs to be properly treated, and the standards to be reached are that the metal elemental iron is 20-60%, the content of iron oxide is 20-60%, and the content of iron element is >65%. If the standards cannot be reached, the iron resources cannot be effectively entered into the molten steel in the electric furnace smelting process, and the power consumption is greatly increased. The high-purity slag iron is selected as the raw material, waste is turned into treasure, the problem of difficult disposal of waste materials is solved, and the iron resources are recovered.

[0036] In the present application, the metal main material structure fully recognizes that the light and thin plate scrap steel has good protection for arc power supply, thereby improving the power supply thermal efficiency. According to the analysis of a large amount of production data, a mathematical model is established to show that the iron resource recovery rate of light and thin plate scrap steel is also comparable to that of heavy scrap. Therefore, the addition amount of light and thin scrap is increased, and the addition amount of heavy scrap is greatly reduced. The traditional process considers that the iron resource recovery rate of heavy scrap is high, which is a good scrap resource, and the addition amount should be increased. However, according to the analysis results of a large amount of production data, this is a wrong understanding.

[0037] The auxiliary materials are added to the furnace charge structure, mainly for rapid slagging, efficient dephosphorization, power saving, and protection of the furnace lining. Power saving and protection of the furnace lining also need to consider the foaming ability of the slag. The pre-melted slag is added for rapid slagging. The pre-melted slag can form a slag pool as soon as possible at the initial stage of smelting, which facilitates the dissolution of lime and dolomite into the slag. The addition amount of lime and the addition amount of dolomite are mainly considered to control the MgO content in the slag between 8-10% to avoid the erosion of refractory materials, and also to ensure that the slag has strong dephosphorization ability. According to the calculation of the amount of SiO2 generated by the oxidation of silicon in the metal main material, the addition amount of lime and dolomite can control the basicity (i.e. the mass ratio of CaO to SiO2) of the final slag between 1.5-2, which has strong foaming ability, thereby playing a role in power saving and protection of the furnace lining. Based on the above considerations and combined with the analysis and research of a large amount of data in the production site, it is concluded that the reasonable addition range of auxiliary materials is lime 20-35 kg / t of molten steel, dolomite 10-15 kg / t of molten steel, and pre-melted slag 3-5 kg / t of molten steel. Because the protection of the furnace lining seriously affects the thermal stop time of the electric furnace smelting process and thus affects the smelting cycle, the auxiliary material structure of the present application can effectively shorten the smelting cycle, reduce the power consumption, and ensure the stable completion of dephosphorization.

[0038] In the auxiliary material, the pre-melted slag first needs to have a low melting point, so the main component is calcium aluminate with low melting point characteristics, that is, the main component CaO is controlled at 30-50%, Al2O3 is controlled at 40-50%, MgO is also added in the pre-melted slag, mainly considering improving the overall slag's ability to not corrode the furnace lining, and SiO2 is also added in the pre-melted slag, which is mainly set to reduce the melting point of the pre-melted slag. Through experiments, the related performance of the pre-melted slag in the application is measured, including melting point measurement and high temperature viscosity measurement, and the pre-melted slag has the functions of good convenient lime and dolomite dissolution and improving the fluidity of the electric furnace slag.

[0039] The electric furnace smelting process based on the structure optimization of the furnace charge in the application specifically includes the following steps:

[0040] S1, the first batch of slag is added to the electric furnace, and then the light and thin plate type scrap steel, high-purity slag iron, scrap steel crushed material, medium-sized scrap steel and heavy scrap steel in the metal main material are added to the electric furnace, and then the molten iron is added;

[0041] The specific process is: after the end of the smelting of the previous furnace, open the furnace cover, before adding the metal main material, first add the first batch of slag at the bottom of the electric furnace molten pool, and then add the light and thin plate type scrap steel, high-purity slag iron, scrap steel crushed material, medium-sized scrap steel and heavy scrap steel in the metal main material by using the material basket, and then add the molten iron. The addition method of the metal main material is: when the electric furnace is a non-continuous scrap steel adding electric furnace, open the furnace cover at the beginning of the electric furnace smelting, add the light and thin plate type scrap steel, high-purity slag iron, scrap steel crushed material, medium-sized scrap steel and heavy scrap steel through the material basket, then add the molten iron, and then cover the furnace cover for smelting. When the electric furnace is a non-continuous scrap steel adding electric furnace with a furnace wall opening iron adding port, open the furnace cover at the beginning of the electric furnace smelting, add the light and thin plate type scrap steel, high-purity slag iron, scrap steel crushed material, medium-sized scrap steel and heavy scrap steel through the material basket, cover the furnace cover to start smelting, and add the molten iron from the iron adding slot of the furnace wall after power on. The above-mentioned addition of the metal main material is all selected to be added at the beginning of smelting (first add scrap steel and then add molten iron), or the molten iron is added from the iron adding slot of the furnace side, mainly to further reduce the number of times of opening the furnace cover to shorten the smelting period, and through the control of the structure of the previous raw material, the above-mentioned addition ability is met.

[0042] S2, the electric furnace is powered on and oxygen blowing smelting is carried out, after 8-15 minutes of power on, the second batch of slag is added for continuous smelting, after the dephosphorization slag is discharged, the third batch of slag is added for continuous smelting, and after the carbon content and temperature of the molten steel reach the tapping requirements, the molten steel is tapped;

[0043] The specific process is as follows: after the first batch of slag and metal main materials are added, the furnace cover is covered, then the power is turned on and oxygen is blown for smelting, after 8-15 minutes of power-on, the second batch of slag is added for continuous smelting, with the smelting process, the scrap steel in the electric furnace is basically melted, and after the dephosphorization slag is discharged through the electric furnace door, the third batch of slag is added for continuous smelting, when the carbon content and temperature of the molten steel meet the tapping requirements, the molten steel is tapped.

[0044] In the above process, the main idea of adding auxiliary materials is to add them in batches, and try to add them before adding the main metal materials; the auxiliary materials are specifically divided into three batches added into the electric furnace, wherein the auxiliary materials include the first batch of slag, the second batch of slag and the third batch of slag. The first batch of slag is added before the main metal materials are added, and the first batch of slag includes lime, dolomite and pre-melted slag; the addition amount of lime in the first batch of slag is 1 / 3-1 / 2 of the total addition amount of lime in the auxiliary materials, the addition amount of dolomite in the first batch of slag is 1 / 3-1 / 2 of the total addition amount of dolomite in the auxiliary materials, and the addition amount of pre-melted slag is the total amount of pre-melted slag in the auxiliary materials; the first batch of slag mainly uses the remaining liquid slag left over from the previous smelting of the electric furnace to quickly promote the dissolution and melting of lime and dolomite, and if the addition amount is too large, it will cause the slag to be not smooth; if it is too small, it will cause the subsequent addition amount of lime to be too large, affecting the smelting process. The second batch of slag includes lime and dolomite; the addition amount of lime in the second batch of slag is 1 / 4-1 / 2 of the total addition amount of lime in the auxiliary materials, and the addition amount of dolomite in the second batch of slag is 1 / 4-1 / 2 of the total addition amount of dolomite in the auxiliary materials; the second batch of slag mainly considers that after 8-15 minutes of power-on, the slag surface has been formed, and the slag contains iron oxide formed by oxygen blowing, which can greatly improve the fluidity of the slag, and it is appropriate to add lime at this time to accelerate the dissolution of the added main metal materials. The third batch of slag is the remaining auxiliary materials after the first batch of slag and the second batch of slag are added in the auxiliary materials, in a specific embodiment, the third batch of slag includes lime and dolomite, the addition amount of lime in the second batch of slag is 1 / 8-1 / 4 of the total addition amount of lime in the auxiliary materials, and the addition amount of dolomite in the third batch of slag is 1 / 8-1 / 4 of the total addition amount of dolomite in the auxiliary materials; the third batch of slag is mainly because after the dephosphorization slag is discharged, the amount of slag in the furnace is greatly reduced, in order to maintain a certain amount of slag to create foamed slag to protect the furnace lining, a certain amount of lime and dolomite need to be added at the end, and the dephosphorization capacity of the slag is continuously improved.

[0045] The electric furnace smelting process based on the charge structure optimization of the application is suitable for both AC electric arc furnace and DC electric arc furnace, and the influence of the charge structure on the arc buried property is considered, that is, the charge structure with good arc buried property in the AC electric arc furnace is also good for the DC electric arc furnace, so the AC electric arc furnace and the DC electric arc furnace are both suitable for the application. The electric furnace capacity suitable for the application is 100-200 tons, because only one basket of solid metal materials such as scrap steel is added in the subsequent process, if the electric furnace capacity is greater than 200 tons, too much solid metal material such as scrap steel needs to be added in two baskets, thereby affecting the smelting cycle of the electric furnace; if the electric furnace capacity is less than 100 tons, the small capacity affects the production line capacity.

[0046] The electric furnace smelting process based on the charge structure optimization of the application is suitable for both AC electric arc furnace and DC electric arc furnace, and the influence of the charge structure on the arc buried property is considered, that is, the charge structure with good arc buried property in the AC electric arc furnace is also good for the DC electric arc furnace, so the AC electric arc furnace and the DC electric arc furnace are both suitable for the application. The electric furnace capacity suitable for the application is 100-200 tons, because only one basket of solid metal materials such as scrap steel is added in the subsequent process, if the electric furnace capacity is greater than 200 tons, too much solid metal material such as scrap steel needs to be added in two baskets, thereby affecting the smelting cycle of the electric furnace; if the electric furnace capacity is less than 100 tons, the small capacity affects the production line capacity.

[0047] Example 1

[0048] The large electric arc furnace in this example has a capacity of 100 tons, and the transformer capacity has an active power of 90 MVA, which is a DC electric arc furnace. The smelting process is as follows:

[0049] (1) After the smelting of the previous furnace is completed, the furnace cover is opened, and 1000 kg of lime, 500 kg of dolomite, and 300 kg of pre-melted slag are added to the bottom of the electric furnace bath, wherein the composition of the pre-melted slag is as follows: CaO: 50%, Al2O3: 42%, MgO: 5%, SiO2: 3%.

[0050] (2) Use the basket to add 43.95 t of light and thin plate scrap steel, 8.79 t of high-purity slag iron, 11.00 t of scrap steel crushed material, 11.00 t of medium scrap steel, and 7.69 t of heavy scrap steel, with a total solid metal material addition of 82.42 t. Among them, the high-purity slag iron contains 45% of elemental iron, 50% of iron oxide, 80% of iron element, and other high furnace slag residues such as CaO, MgO, SiO2, P2O5, and Al2O3, with a P2O5 content of 0.3%.

[0051] (3) When the solid metal material addition is completed, 27.47 t of molten iron is added through the ladle.

[0052] (4) Then start power-on and oxygen blowing smelting, and after 10 minutes of power-on, add the second batch of slag material, including 500 kg of lime and 250 kg of dolomite.

[0053] (5) As the smelting proceeds, when the power-on time reaches 15 min, the scrap steel in the furnace is basically melted, at which time the electric furnace smelting discharges dephosphorization slag through the furnace door, and after the dephosphorization slag is discharged, the third batch of slag material is added, including 500 kg of lime and 250 kg of dolomite.

[0054] (6) When the power is on for 25 min, the carbon content and temperature of the molten steel meet the tapping requirements, and the tapping starts, the tapping amount reaches 101 tons, the molten steel yield is 91%, the power consumption per ton of steel is 254 KWh / t, and the smelting cycle is 38 min.

[0055] In the conventional process, the heavy scrap steel is added in an amount of more than 30 tons, the light and thin scrap steel is added in an amount of less than 20 tons, the tapping amount is only 100 tons, the molten steel yield is 90%, the power consumption per ton of steel is 280 KWh / t, and the smelting cycle is 40 min. As can be seen from the above, by optimizing the furnace charge structure in the embodiment, while the metal yield is basically maintained or even improved, the power consumption per ton of steel is reduced by 26 KWh / t, and the smelting cycle is shortened by 2 min.

[0056] Example 2

[0057] The large-scale electric arc furnace in this embodiment has a capacity of 150 tons, and the transformer has an active power of 130 MVA, which is an alternating current electric arc furnace. The charging method in the smelting process is as follows:

[0058] (1) After the smelting of the previous furnace is completed, the furnace cover is opened, and lime 2250 kg, dolomite 750 kg, and pre-melted slag 600 kg are first added to the bottom of the electric furnace bath. The composition of the pre-melted slag is as follows in terms of mass percentage: CaO: 45%, Al2O3: 45%, MgO: 7%, SiO2: 3%.

[0059] (2) Use the basket to add light and thin plate scrap steel 63.93 t, high-purity slag iron 9.89 t, scrap steel crushed material 9.89 t, medium scrap steel 8.24 t, and heavy scrap steel 8.24 t, for a total of 102.2 t of solid metal in the main metal charge. Among them, the high-purity slag iron contains 40% elemental iron, 50% iron oxide, 75% iron content, and other high furnace slag residues such as CaO, MgO, SiO2, P2O5, and Al2O3, with a P2O5 content of 0.2%.

[0060] (3) When the solid metal charge is completed, 62.24 t of molten iron is added through the ladle.

[0061] (4) Then start the power-on and oxygen blowing smelting, and after 11 minutes of power-on, add the second batch of slag, including lime 1687.5 kg and dolomite 562.5 kg.

[0062] (5) As the smelting proceeds, when the power is on for 16 min, the scrap steel in the furnace is basically melted at this time, and the electric furnace smelting discharges dephosphorization slag through the furnace door. After the dephosphorization slag is discharged, the third batch of slag is added, including lime 562.5 kg and dolomite 187.5 kg.

[0063] (6) When the power is on to 27 min, the carbon content and temperature of the molten steel reach the tapping requirements, the tapping starts, the tapping amount reaches 152 tons, the molten steel yield is 91.5%, the power consumption per ton of steel is 240 KWh / t, and the smelting cycle is 42 min.

[0064] However, in the conventional process, the heavy scrap steel is added in an amount of more than 45 tons, the light and thin scrap steel is added in an amount of less than 30 tons, the tapping amount is only 150 tons, the molten steel yield is 90%, the power consumption per ton of steel is 265 KWh / t, and the smelting cycle is 44 min. It can be seen that in the embodiment, by optimizing the electric furnace charge structure, the metal yield is basically maintained or even improved, while the power consumption per ton of steel is reduced by 25 KWh / t, and the smelting cycle is shortened by 2 min.

[0065] Example 3

[0066] The large-scale electric arc furnace in this embodiment has a capacity of 200 tons, and the transformer has an active power of 160 MVA, which is an alternating current electric arc furnace. The charging method in the smelting process is as follows:

[0067] (1) After the smelting of the previous furnace is completed, the furnace cover is opened, and lime 2333 kg, dolomite 1000 kg, and pre-melted slag 1000 kg are first added to the bottom of the electric furnace bath. The composition of the pre-melted slag is as follows in terms of mass percentage: CaO: 43%, Al2O3: 50%, MgO: 4%, SiO2: 3%.

[0068] (2) Light and thin plate scrap steel 76.92 t, high-purity slag iron 13.19 t, scrap steel crushed material 13.19 t, medium scrap steel 11.00 t, and heavy scrap steel 6.59 t are added together using a charging basket. The total amount of solid metal in the main metal charge is 120.88 t. The high-purity slag iron contains 45% elemental iron, 50% iron oxide, 80% iron, and other high furnace slag residues such as CaO, MgO, SiO2, P2O5, and Al2O3. The P2O5 content is 0.35%.

[0069] (3) After the solid metal charge is completed, 98.9 t of molten iron is added through a ladle.

[0070] (4) Then the power is turned on and oxygen is blown for smelting. When the power is on for 14 minutes, the second batch of slag is added, including lime 3500 kg and dolomite 1500 kg.

[0071] (5) As the smelting proceeds, when the power is on to 17 min, the scrap steel in the furnace is basically melted. At this time, the electric furnace smelting discharges dephosphorization slag through the furnace door. After the dephosphorization slag is discharged, the third batch of slag is added, including lime 1166 kg and dolomite 500 kg.

[0072] (6) When the power is on to 30 min, the carbon content and temperature of the smelted molten steel reach the tapping requirements, the tapping starts, the tapping amount reaches 203 tons, the molten steel yield is 91.5%, the power consumption per ton of steel is 245 KWh / t, and the smelting cycle is 45 min.

[0073] In the conventional process, the heavy scrap steel is added in an amount of more than 60 tons, the light and thin scrap steel is added in an amount of less than 40 tons, the tapping amount is only 200 tons, the molten steel yield is 90%, the power consumption per ton of steel is 265 KWh / t, and the smelting cycle is 50 min. It can be seen that in the embodiment, by optimizing the electric furnace burden structure, the metal yield is basically maintained or even improved, the power consumption per ton of steel is reduced by 20 KWh / t, and the smelting cycle is shortened by 5 min.

[0074] Those skilled in the art of the present technology should recognize that the above embodiments are only used to illustrate the present application, and are not used as a limitation on the present application, as long as the changes and modifications of the above described embodiments are within the spirit and principles of the present application, they will fall within the scope of the claims of the present application.

Claims

1. An electric furnace smelting process based on burden structure optimization, characterized in that, The metal main material used in the electric furnace smelting process comprises the following components by mass percentage: molten iron: 25-45%; light and thin plate scrap steel: 24-42%; high-purity slag iron: 6-18%; scrap steel crushed material: 6-12%; medium scrap steel: 5-12%; heavy scrap steel: 0-9%; The auxiliary material used in the electric furnace smelting process comprises the following components: lime 20-35 kg / t of molten steel; dolomite 10-15 kg / t of molten steel; pre-melted slag: 3-5 kg / t of molten steel, The method comprises the following steps: S1, adding the first batch of slag material into the electric furnace, and then adding the light and thin plate scrap steel, high-purity slag iron, scrap steel crushed material, medium scrap steel and heavy scrap steel in the metal main material into the electric furnace, and then adding the molten iron; S2, powering on the electric furnace and blowing oxygen smelting, after 8-15 minutes of power-on, adding the second batch of slag material to continue smelting, discharging the dephosphorization slag, and then adding the third batch of slag material to continue smelting, and then tapping the molten steel when the carbon content and temperature of the molten steel reach the tapping requirements; The auxiliary material is added into the electric furnace in three batches, and the auxiliary material comprises the first batch of slag material, the second batch of slag material and the third batch of slag material, The first batch of slag material comprises lime, dolomite and pre-melted slag; the addition amount of lime in the first batch of slag material is 1 / 3-1 / 2 of the total addition amount of lime in the auxiliary material, the addition amount of dolomite in the first batch of slag material is 1 / 3-1 / 2 of the total addition amount of dolomite in the auxiliary material, and the addition amount of pre-melted slag is the total amount of pre-melted slag in the auxiliary material; The second batch of slag material comprises lime and dolomite; the addition amount of lime in the second batch of slag material is 1 / 4-1 / 2 of the total addition amount of lime in the auxiliary material, and the addition amount of dolomite in the second batch of slag material is 1 / 4-1 / 2 of the total addition amount of dolomite in the auxiliary material; The third batch of slag material is the remaining auxiliary material after the first batch of slag material and the second batch of slag material are added into the auxiliary material.

2. The electric furnace smelting process based on burden structure optimization according to claim 1, characterized in that, In the step S1, the metal main material is added in the following manner: The electric furnace with non-continuous scrap steel adding is used, the furnace cover is opened at the beginning of electric furnace smelting, the light and thin plate scrap steel, high-purity slag iron, scrap steel crushed material, medium scrap steel and heavy scrap steel are added through a basket, then the molten iron is added, and then the furnace cover is covered for smelting; or The electric furnace with non-continuous scrap steel adding and a furnace wall with an iron adding opening is used, the furnace cover is opened at the beginning of electric furnace smelting, the light and thin plate scrap steel, high-purity slag iron, scrap steel crushed material, medium scrap steel and heavy scrap steel are added through a basket, the furnace cover is covered for smelting, and the molten iron is added from the iron adding slot of the furnace wall after power-on.

3. The electric furnace smelting process based on burden structure optimization as claimed in claim 1, wherein, The third batch of slag material comprises lime and dolomite, the addition amount of lime in the third batch of slag material is 1 / 8-1 / 4 of the total addition amount of lime in the auxiliary material, and the addition amount of dolomite in the third batch of slag material is 1 / 8-1 / 4 of the total addition amount of dolomite in the auxiliary material.

4. The electric furnace smelting process based on burden structure optimization as claimed in claim 1, wherein, In the metal main material, the high-purity slag iron is a block-shaped raw material obtained by processing a mixture of iron slag produced in blast furnace iron smelting; the content of iron element in the high-purity slag iron is >65wt%, and the content of P2O5 is <0.5wt%.

5. The electric furnace smelting process based on burden structure optimization as claimed in claim 1 wherein, The pre-melted slag comprises the following components in percentage by mass: CaO: 30-50%, Al2O3: 40-50%, MgO: 4-8%, SiO2: 3-10%.

6. Electric furnace smelting process based on burden structure optimization according to any one of claims 1 to 5, characterized in that, The capacity of the electric furnace is 100-200 tons.